When Johnson, who is not on trial, replied positively, Contogoulas thanked him, setting out his plans for retirement.

On January 1, 2006, Contogoulas emailed Johnson saying: "Need a high 1m if possible for the next few days."

When Johnson replied "I'm going 58", the trader responded: "You are a star, as always. When I quit this business and write a book about it, I will write good things about you. Hehe."

However, Johnson did not appear too keen on his practise being made public, jurors heard.

After making another request some months later, Contogoulas wrote: "Remember, when I retire and write a book about this business, your name will be written in golden letters and you will have an open invitation to my bar in the Greek islands. Hehe."

But Johnson replied: "I would prefer this not to be in any books."

Speaking on the second day of his opening, prosecutor James Hines QC, told the jury at London's Southwark Crown Court: "There cannot have been any doubt, at that stage, about whether Mr Johnson wanted any of this in the public domain."

Contogoulas is accused alongside Jonathan James Mathew, 35, Jay Vijay Merchant, 45, Alex Pabon, 37, and Ryan Reich, 34, of manipulating the US Dollar London Interbank Offered Rate between June 1 2005 and August 31 2007.

The charge states that they dishonestly agreed to procure or make submissions of rates by Barclays, a panel bank, into the Dollar Libor setting process which were false or misleading.

Mr Hines told the court the traders were dealing with "eye-watering" sums of money.

New York-based Merchant, Pabon and Reich allegedly either told Contogoulas what they wanted, and he in turn told submitters Mathew or Johnson, or the request was made directly.

He said the parties the bankers are alleged to have defrauded "were entitled to assume that it was a given that they were dealing with Barclays fair and square, honestly and on a level playing field".

Jurors heard they were also entitled to assume the rate was an "honest, accurate and reliable industry benchmark".

Referring to the traders, Mr Hines said: "The defendants in this case are all very successful, intelligent, well educated and experienced professionals.

"These men were trusted by Barclays Bank to trade in deals worth billions of dollars. There are some occasions where the defendants will refer to deals involving eye-watering sums of money."

He added that "making money was the name of the game", and jurors heard the men had incomes ranging from hundreds of thousands of pounds into the millions.

Mathew, from Shenfield in Essex, Contogoulas, from Greece, and Merchant, Pabon, and Reich, all of whom live in America, deny one count of conspiracy to defraud.